Site Mobile Navigation

One Prairie Dog Plays Critical Role in Wisconsin

Contact with one prairie dog has accounted for more than half of the 34 human cases of monkeypox in Wisconsin, a state health official said yesterday.

The people affected in 18 cases in Wisconsin -- three confirmed, six probable and nine suspected -- were exposed to the prairie dog as it was moved from place to place, said Dr. Jeffrey P. Davis, the Wisconsin state epidemiologist.

''The prairie dog was a super-transmitter if there ever was one,'' Dr. Davis said in a telephone news conference, referring to the term used when a single human or animal passes a virus to many people. ''The prairie dog was moved quite a bit from a pet store to a household to one veterinary clinic and then to a second veterinary clinic before it died,'' Dr. Davis said.

The virus that causes monkeypox is usually transmitted by contact with lesions on the skin. But federal health officials have recommended that health care workers use protections against the possibility of airborne transmission. Wisconsin officials said that in a small number of cases those who got the virus from an animal did not appear to have had direct contact with that animal.

One Wisconsin resident who apparently caught monkeypox from the prairie dog had ''minimal'' contact with the infected animal but slept in the same room as the caged animal, Dr. Davis said. Also, ''a substantial number of individuals in one particular veterinary clinic became ill as a result of'' direct contact, Dr. Davis said. ''We are trying to understand what that all means, precisely what the contact was.''

''There certainly was a lot of transmission associated with the movement of this animal from place to place and with contact with this animal, once the animal was in those settings,'' Dr. Davis said.

Epidemiologists are tracing prairie dogs and other animals that were sold or traded in the Upper Midwest as part of an investigation into the first ever outbreak of monkeypox in the Americas.

At least 51 additional human monkeypox cases are under investigation in three other states in the outbreak, the Centers for Disease Control and Prevention in Atlanta said. They include 33 in Indiana, 17 in Illinois and 1 in New Jersey.

The number of cases under investigation in Wisconsin rose by 13 yesterday, partly as a result of the publicity that health officials are seeking in encouraging people to report any suspected illness.

Of the 34 cases under investigation in Wisconsin, 14 occurred in veterinarians or veterinary technicians; 8 in exposure to animals in pet stores; 7 in people who had contact with prairie dogs in a household; 3 who may have had exposure to prairie dogs in households other than their own; and 2 in health care workers.

Tests are pending on three suspected cases in which human-to-human transmission of monkeypox may have occurred. Dr. Davis said it appeared unlikely that the cases would turn out to be monkeypox.

Some suspected cases have arisen from people who visited pet stores where infected animals had been housed. In one case, Dr. Davis said, a customer visited a pet store for a substantial amount of time to buy a reptile. It is not clear whether the customer handled an infected animal in the store.

In another case, a customer visited a pet store and did not have any contact with prairie dogs, but had been scratched by another animal. Jo Napolitano contributed to this article.